The genus Trichoderma consist of filamentous fungi that exhibit sensitivity to fungicides, phytoalexins and essential oils whose antibiotic activity is confirmed. Nowadays it is widely known that molecules in hyphae cell membrane, so called ABC transporters play a major role in mechanism of resistance in filamentous fungi, this includes species of genus Trichoderma as well. Some ABC transporters have been detected in the species Trichoderma viride. In this laboratory experiment the influence of essential oils (mint, sage and lavender) on Trichoderma viride was tested. The experiment was conducted in randomized block design in eight variants so there was 48 petrii dishes overall. The results are quantified with the Index of inhibition and were checked statistically with analysis of variance. In this laboratory experiment the strongest influence of essential oil on Trichoderma viride was exhibited by mint oil when tested on supstrate (73% the fourth day and 47% on the seventh) and lavender oil when tested for volatile influence (62% the fourth day and 47% on the seventh).